Automatic wear compensator for a screw-type brake

ABSTRACT

An automatic friction lining compensator adaptable to a screwtype brake applied either mechanically or by springs. Essentially, a shaft having a screw on one end threadably received in the piston causes movement of the piston upon rotation of the shaft. Rotation is imparted to the shaft by an arm operating through a one-way clutch. The arm is returned to its initial position after actuation of the brake. A second arm is connected to the shaft through a one-way clutch operating in the reverse direction to that associated with the first arm. The shaft is returned towards its initial position by movement of the second arm. However, movement of the second arm greater than a predetermined distance causes release of the one-way clutch associated with the second arm, thereby limiting the return of the shaft to its initial angular position. In this way, compensation for the wear of a friction material actuated by the piston is accomplished.

United States Patent Primary Examiner-Duane A. Reger Att0rne vs-F.W.Brunner. P.E. Milliken and Oldham &

Oldham ABSTRACT: An automatic friction lining compensator adaptable to ascrew-type brake applied either mechanically or by springs. Essentially.a shaft having a screw on one end threadably received in the pistoncauses movement of the piston upon rotation of the shaft. Rotation isimparted to the shaft by an arm operating through a one-way clutch. Thearm is returned to its initial position after actuation of the brake. Asecond arm is connected to the shaft through a one-way clutch operatingin the reverse direction to that associated with the first arm. Theshaft is returned towards its initial position by movement of the secondarm. However, movement of the second arm greater than a predetermineddistance causes release of the one-way clutch associated with the secondarm, thereby limiting the return of the shaft to its initial angularposition. In this way, compensation for the Wear of a friction materialactuated by the piston is accomplished.

[72] inventor Carl E. Bricker Cuyahoga Falls, Ohio [21] Appl. No.774,438 [22] Filed Nov. 8, 1968 [45] Patented Feb. 2, 1971 [73] AssigneeThe Goodyear Tire & Rubber Company Akron, Ohio a corporation of Ohio[54] AUTOMATIC WEAR COMPENSATOR FOR A SCREW-TYPE BRAKE 8 Claims, 7Drawing Figs.

52] us. Cl 188/196, 188/171 [51] Int. Cl F16d 65/56 [50] Field of Search188/72.73C. 79.5K, 196, 196RR,166 171 [56] References Cited 7 UNITEDSTATES PATENTS 3,115,217 12/1963 Butler ..188/196(RR)X IVPATENTEUFEB2|97| 7 5 7 SHEET 1 0F 2 FIG.2

INVENTOR.

CARL E. BRICKER wmwwm AT TORN EYS PATENT EUFEB 2mm 3.559774 sum 2 or 2FIG.3

ATTORNEYS.

AUTOMATIC WEAR COMPENSATOR FOR A SCREW- TYPE BRAKE Heretofore it hasalways been a problem in threaded brakes actuated either by spring forceor mechanically to automatically compensate for friction lining wear sothat the same arcuate movement of the actuating lever can always takeplace regardless of lining wear. A lining wear compensator is needed tomeet these requirements of the brake art.

The general object of the invention is tov provide an extremely simple,yet highly reliable and effective lining wear compensator forassociation with a screw-type brake which is applied either mechanicallyor by spring action.

The aforesaid object of the invention and other objects which willbecome apparent as the description proceeds are achieved by providing ina lining wear compensator for a brake, the combination of a housing, ablock slidably carried by the housing, friction material carried by theblock, and a shaft rotatably received in nonsliding relation through thehousing and threadably engaging the block which is characterized by armmeans operating through a one-way clutch to apply torque to the shaft inone direction for a limited distance of movement to apply the brake,means to return the arm means through the same distance of movement whenbraking release is desired, lever means actuated by the means to returnthe arm means connected to the shaft through a second oneway clutchreversed from the first one-way clutch, and means to release theclutching action of the second one-way clutch when the lever means hasmoved a predetermined distance.

For a better understanding of the invention, reference should be had tothe accompanying drawings wherein:

FIG. 1 is a perspective schematic illustration of the principles andstructural characteristics of the invention;

FIG. 2 is an enlarged, broken-away cross-sectional illustration of oneembodiment of the invention incorporating the principles of FIG. 1;

FIG. 3 is a side elevation of a modified embodiment of the invention;

FIG. 4 is an end elevation of the embodiment of FIG. 3;

FIG. 5 is a broken-away plan view of the pivoted support for theembodiment of FIG. 3;

FIG. 6 is a broken away plan view of the friction elements utilized inthe embodiment of FIG. 3; and

With reference to the schematic illustration of the invention shown inFIG. 1, the numeral 10 indicates generally a shaft which has a screw 12integrally formed on one end thereof. The screw 12 will normally engagewith some type of piston (not shown) so that rotation of the screw 12causes axial displacement of the piston with respect to the shaft 10,and hence either actuation of a brake or deactuation depending upon thedirection of rotation of screw 12.

No rotatable support to shaft 10 is shown, although it should beunderstood that any suitable bearing means to support shaft 10 will meetthe objects of the invention.

The essence of the invention, however, is achieved by the method toachieve rotational actuation of shaft 10, in combination with a limitedreturn movement of the shaft depending upon wear of the brake liningsactuated by a screw 12. To this end, three arms or levers A. B, and C,designated by nu meral I4, 16, and 18, respectively, are mounted toshaft 10 in the following manner: lever or arm A is mounted with aspring clutch around shaft 10 which clutch 20 is connected in fixedangular relationship with respect to arm A by an extended portion 200held in fixed relationship by a pin 22 affixed to arm A. The other endof spring clutch 20, as depicted by dotted arm 20b, connects in behindarm B, and is actuated thereby. Arm C connects through a one-way rolleror spring clutch 24 so that in the schematic illustrated it can onlyapply rotative to shaft 10 in a counterclockwise direction.

Hence, in operation the schematic is designed for a spring applied brakenormally utilized in a fail-safe condition. In this instance, some typeof positive pressure means such as an air cylinder or electricsolenoidwill apply a permanent force f, against arms B and C asindicated by arrows 26 to hold the brake in the nonactuated position.When such force f, is released. a spring force f, indicated by arrow 28is applied to the end of lever or arm C to cause roller clutch 24 toactuate and turn shaft 10 counterclockwise to advance the piston bymeans of screw 12 and apply the brake.

Because of the frictional relationship of the arms A and B throughspring clutch 20 to shaft 10, the rotation of arm C also carries arms Aand B along with the rotation of shaft 10 until arm A is restrained fromfurther movement by a stop 30. The movement of arms A and B is from adotted line position indicated by numeral 32 through an angle indicatedby numeral 34. If the brake is not applied by the time levers A and Bhave moved through angle 34, additional travel represented by angle 36of lever arm C is permitted to the dotted line position 38. When thebrake is released by the application of force 1",, arm C moves throughangle 36 without turning shaft 10 until arm B is picked up by the forcef,. Arm A moves with arm B because of the same frictional relationthrough clutch 20. When arm B is returned through angle 34, the actionof arm B on end 20b of spring clutch 20 causes rotation of shaft 10 toeffect release of the brake. Thus, on the next application, the brakewill apply when rotation of shaft 10 of an amount equal to angle 34 hasbeen utilized unless lining wear requires an additional rotation say ofan amount equal to angle 36, as explained above. Hence, for eachapplication of the brake the wear of the lining on the previousapplication is compensated so that brake application is always takencare of within the available power of spring force )2, and thestructural advancing requirements of screw 12.

Naturally, it must be understood that the schematic shown in FIG. 1merely exemplifies the principles necessary to achieve the objects ofthe invention, and that the structural requirements of the brake can beof many and varied combinations, and can work with a mechanical orspring actuation in a manner similar to or opposite that shown in theschematic. Further, while the clutch associated with arms A and B shouldpreferably be a spring clutch, the clutch associated with arm C can beany type of one-way acting clutch, such as a roller clutch or a springclutch. The essence of the invention, however, is achieved by utilizingtwo simple one-way clutches mounted to the same shaft in oppositerelationship to allow overriding of the one clutch upon the actuatingmovement of the other clutch whereby return of the actuating arm doesnot pick up the first clutch until that amount of angular motionnecessary to compensate for lining wear is adjusted for before the shaftis rotated to the brake release position.

A typical structural embodiment of the invention is illustrated in FIG".2 of the drawings where a brake housing is illustrated by numeral 50which slidably carries a piston 52 held against rotatable relationshipby a guide pin 54. Similar portions of this structure to thoseillustrated in the schematic are indicated by the same numeral with thesuffix a attached. Hence, a screw 12a forming an integral part of shaftis actuated by a lever arm 18 operating through a one-way roller clutch24a. The piston 52 carries a friction block 56 which when moved axiallyin the direction indicated by arrow 58 applies the brake in the usualmanner. The compensating action is applied by arms 14 and 16, eachconnected in a respective manner to shaft 10a by a spring clutch 20a. Inorder to allow for rotation of shaft 10a within housing 50 without anyaxial movement of such shaft with respect to the housing upon rotationthereof, any convenient means maybe utilized, but a slip ring 60 isillustrated which snaps into place around shaft 100 allowing rotationthereof, but affixing the relationship axially of the shaft to housing50, all in the conventional manner known in the art. Hence, rotation ofshaft 10a causes axial movement of piston 52 in a direction dependentupon the direction of rotation of the shaft 10a.

Hence, it should be understood with reference to FIG. 2 that arm 18aapplies the brake through the one-way roller clutch 1 24a. Arm 16areleases the brake through the spring clutch 20a, while arm 14a stopsthe release travel after a preselected angular rotation of shaft 10a toallow for wear compensation, as described with reference to FIG. 1above. Some type of stop with relationship to arm 14a is necessary toachieve the objects of the invention. In essence, arm 14a merelyprovides an extension to the one end of spring clutch 20a while arm 1616a merely provides an extension to the other end of the spring clutch200.

For a better understanding of the application to an actual brake,reference should be had to FIGS. 3-6. This modification comprises a pairof I-shaped carrying frames 100 and 102 which are mounted at one end, asshown in FIG. 5, by support brackets 100a and 102a, respectively,pivotally carried on appropriate pins and l02b. Each of the beams 100and 102 carries a friction block 104 and 106, respectively, supportedand mounted by appropriate lock nuts 104a and 106a, as is bestillustrated in FIG. 6 of the drawings. The friction blocks clamp onto arotating disc 108 to provide braking thereof.

The brake is actuated by a spring-type brake actuator indicatedgenerally by numeral 110, as seen in FIG. 3. A suitable brake actuatorfor this purpose would be a Bendix- Westinghouse Piece 0275787 which isspring actuated and released by air pressure. The actuator 110 operatesthrough a rod 112 connected in adjustable relationship to a linkage 114.Linkage 114 is pivotally connected to an actuating arm 116. The arm 116is slidably received over an actuating sleeve 118 as best seen in FIG. 4of the drawings. The a sleeve 118 is fixedly mounted to a screw 120 bymeans of suitable pin 118a. The screw 120 is threaded in oppositedirections on either end. The screw 120 is threadably received inappropriate actuating sleeves 122 and 124, respectively, which aremounted in pivotal relationship to the beams 100 and 102 by appropriatepins 122a and 1240. It should be understood that rotation of the screw120 in one direction draws the sleeves 122 and 124 closer together,whereas rotation of the screw 120 in the other direction moves thesleeves 122 and 124 further apart, but both movements being in equal anand opposite directions, as is conventional with this type of screw,normally associated with a turnbuckle arrangement, or the like.

The essence of the invention is incorporated in the clutches associatedwith the arm 116, and this association is substantially the same as inthe prior embodiments of the invention. Essentially, an actuating springclutch 130 is mounted so as to have its one end 130a fixed under plate132 which is held to arm 116 by appropriate screws 132a. Thus, it shouldbe understood that spring clutch 130 is fixedly mounted to arm 116 andhas its other end freely sliding over shaft 118 whereby rotation of arm116 in the direction indicated by arrow 134 in FIG. 3 causes atightening of the spring clutch 130 around shaft 118 and rotation of thescrew 120 in that direction. The other half of the clutch combination isprovided by a spring clutch 136 which is also slidably received inclose-fitting relationship over shaft 118 and has the internal endthereof bent up in a hook form at 136a to fit over the width of arm 116.The opposite end 136b of spring clutch 136 rides freely over sleeve 118,but will hit the web 102a of the frame 102 on that side after a certaindegree of rotation of arm 116 in the direction of arrow 134.

Hence, in operation, the actuator 110 is normally in the positionillustrated in FIG. 3 of the drawings, but when braking action isrequired, the spring is actuated causing rotation of arm 116 in thedirection of arrow 134 which applies the brake by drawing the frames 100and 102 closer together. Upon release of actuator 110, the arm 116rotates in the direction of an arrow 134a which automatically releasesspring clutch 130 and when arm 116 engages the hooked end 1360 of spring136, the screw 120 is rotated in the opposite direction and the brake isreleased. Naturally, if lining wear has occurred during the brakeapplication, the other end of spring clutch 136 will have engaged frame102 causing the hooked end 1360 to lift off arm 116. It is with thisamount of arcuate clearance that there is no rotation of screw 120 evenupon rotation of arm 116 until arm 116 picks up the hooked end 136a uponthe return of actuator 110 to its normal positron.

Hence, it is seen that an extremely simple, yet highly effective dualclutch wear compensation is utilized in this brake which is preferablyused for fail-safe operation. Again, it should be stressed that whiletwo spring actuated clutches are shown, only clutch 136 need actually bea spring clutch to achieve the objects of the invention, and any one-wayclutching mechanism may be utilized in place of spring clutch 130. Sincebrake application takes place through spring clutch 130, as shown inFIG. 4 of the drawings, this spring is of considerably heavierconstruction than spring clutch 136 which only returns the brake to itsdeactuated position.

While in accordance with the patent statutes only one best knownembodiment of the invention has been illustrated and described indetail, it is to be particularly understood that the invention is notlimited thereto or thereby, but that the inventive scope is defined inthe appended claims.

I claim:

1. In a lining wear compensator for a brake the combination of ahousing, a block slidably carried by the housing, friction materialcarried by the block, and a shaft rotatably received in nonslidingrelation through the housing and threadably engaging the block which ischaracterized by;

arm means operating through a one-way clutch to apply torque to theshaft in one direction and for a limited distance of movement to applythe brake;

means to return the arm means through the same distance of movement whenbraking release is desired;

lever means actuated by the means to return the arm means connected tothe shaft through a second one-way clutch reversed from the firstone-way clutch; and

means to release the clutching action of the second one-way clutch whenthe lever means has moved a predetermined distance.

2. A lining wear compensator according to claim 1 where the secondone-way clutch is a spring clutch.

3. A lining wear compensator according to claim 2 where the lever meansis connected to one end of the spring clutch and the means to releasethe clutching action of the second one-way clutch is connected to theother end of the spring clutch, and means to positively engage and limitthe means to release the clutching action of the second one-way clutch.

4. A lining wear compensator according to claim 1 where the arm means isactuated by a spring for fall-safe type braking action, and the means toreturn the arm means is a positive mechanical actuation.

5. A lining wear compensator according to claim 1 where the arm means isactuated by a positive mechanical actuation and the means to return thearm means is a spring.

6. A lining wear compensator for a screw-type brake which included:

means for brake actuation of a fail-safe type;

a shaft with a screw thread on at least one end thereof adapted tothreadably engage with the means for brake actuation;

a pair of opposed one-way clutch means associated with the shaft;

at least one lever means to effect rotation to the shaft in onedirection through one of the one-way clutch means, and in the otherdirection through the one-way clutch means, said brake actuation beingby a spring action which acts through one of the lever means to providea limited angular rotation of the shaft; and

means to limit the one-way clutching action of the one-way clutch notutilized during brake actuation when angular movement of the shaft toreturn to its original position goes beyond a predetermined angularrotation.

7. A compensator according to claim 6 where separate lever means areassociated with each end of the spring and a positive stop mounted sothat the one of said lever means which acts to release the clutchingaction engages with the stop to limit the one-way clutching action ofthe spring.

8. A compensator according to claim 6 where the means for brakeactuation includes a pair of pivoted frame means, fricremovably engagingthe lever means, and the other end engaging one of the frame means toachieve the limited clutching action desired.

UNITED STATES PATENT OFFICE Patent No.

Dated February 2, 1971 Inventorfll) 0E1 E Bricker It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 111+,

Column 2,

Column L after "and" insert --Fig. 7 1s a fragmentary sectional viewtaken along the lines 7-? of Fig. 14

after "clutch", delete "1".

after "arm", delete "16'';

"0275787" should read --#275787-.

"fell-safe" should read --fail-safe--;

"included" should read --1 nc1udes-.

Signed and sealed this 13th day of July 1971.

(SEAL) Attest:

EWARD M.FLETGHER,J'R.

Attesting Officer WILLIAM E. SCHUYLER, Commissioner or Patem

1. In a lining wear compensator for a brake the combination of : ahousing, a block slidably carried by the housing, friction materialcarried by the block, and a shaft rotatably received in nonslidingrelation through the housing and threadably engaging the block which ischaracterized by; arm means operating through a one-way clutch to applytorque to the shaft in one direction and for a limited distance ofmovement to apply the brake; means to return the arm means through thesame distance of movement when braking release is desired; lever meansactuated by the means to return the arm means connected to the shaftthrough a second one-way clutch reversed from the first one-way clutch;and means to release the clutching action of the second one-way clutchwhen the lever means has moved a predetermined distance.
 2. A liningwear compensator according to claim 1 where the second one-way clutch isa spring clutch.
 3. A lining wear compensator according to claim 2 wherethe lever means is connected to one end of the spring clutch and themeans to release the clutching action of the second one-way clutch isconnected to the other end of the spring clutch, and means to positivelyengage and limit the means to release the clutching action of the secondone-way clutch.
 4. A lining wear compensator according to claim 1 wherethe arm means is actuated by a spring for fall-safe type braking action,and the means to return the arm means is a positive mechanicalactuation.
 5. A lining wear compensator according to claim 1 where thearm means is actuated by a positive mechanical actuation and the meansto return the arm means is a spring.
 6. A lining wear compensator for ascrew-type brake which included: means for brake actuation of afail-safe type; a shaft with a screw thread on at least one end thereofadapted to threadably engage with the means for brake actuation; a pairof opposed one-way clutch means associated with the shaft; at least onelever means to effect rotation to the shaft in one direction through oneof the one-way clutch means, and in the other direction through theone-way clutch means, said brake actuation being by a spring actionwhich acts through one of the lever means to provide a limited angularrotation of the shaft; and means to limit the one-way clutching actionof the one-way clutch not utilized during brake actuation when angularmovement of the shaft to return to its original position goes beyond apredetermined angular rotation.
 7. A compensator according to claim 6where separate lever means are associated with each end of the springand a positive stop mounted so that the one of said lever means whichacts to release the clutching action engages with the stop to limit theone-way clutching action of the spring.
 8. A compensator according toclaim 6 where the means for brake actuation includes a pair of pivotedframe means, friction blocks carried by each frame means, the shaftbeing threaded on each end in opposite directions and threadablyreceived in the free ends of the frame means, and one of said clutchmeans being a spring clutch which has one end thereof removably engagingthe lever means, and the other end engaging one of the frame means toachieve the limited clutching action desired.